body {
    font-family: Arial, sans-serif;
    margin: 20px;
}
.container {
    max-width: 800px;
    margin: 0 auto;
}
.mode-select {
    text-align: center;
    margin-top: 50px;
}
.btn {
    display: inline-block;
    padding: 15px 30px;
    margin: 10px;
    border-radius: 5px;
    text-decoration: none;
    color: white;
}
.teacher-mode {
    background-color: #4CAF50;
}
.student-mode {
    background-color: #2196F3;
}
#question-container {
    padding: 20px;
    border: 1px solid #ddd;
    margin: 20px 0;
}
button {
    padding: 10px 20px;
    margin: 5px;
    cursor: pointer;
}